Melbourne, Australia (SportsNetwork.com) - After months of preparation and testing, 10 teams and 20 drivers are ready to get the 2015 Formula One season underway with this weekend's Australian Grand Prix.

Lewis Hamilton and Mercedes are also set to begin their driver and constructors' title defenses. This season will feature a record-tying 20-race calendar, which will conclude Nov. 29 in Abu Dhabi.

Last year, Hamilton won 11 of the 19 races and finished the season 67 points ahead of his Mercedes teammate and championship rival Nico Rosberg. It was the second F1 world championship for Hamilton. Mercedes clinched its first constructors' title when Hamilton won the Russian Grand Prix, as three races remained in the season.

Mercedes won 16 grand prix during the 2014 season, beginning with Nico Rosberg's victory in Australia. Rosberg went on to score four more wins last year.

Rosberg's attempt to win a second straight Australian GP got off to a good start on Friday, as he led the way in the two practice sessions. The German's quickest lap around the Albert Park Circuit during P1 was clocked in 1 minute, 29.557 seconds. His time of 1:27.697 topped the charts in P2.

"It was great to be back in the car at this awesome track," Rosberg said. "Today, we have the evidence that our Silver Arrow is quick again, and it was a great start for the team. I was very happy with my long run, but on one lap, I still need to work on the pace, as I had a lot of oversteer in the car."

Hamilton had the second fastest lap in each of the two practices. He was only 0.029 seconds behind Rosberg in P1 and just 0.1 seconds in back of his teammate in P2. Hamilton has yet to win the Australian GP. He claimed the pole for last year's race here, but after completing only two laps, he was forced to retire due to engine failure.

"It feels great to be back on track and back into a race weekend," Hamilton said. "I'm not 100 percent comfortable with the car, but that's to be expected on the first day. (Friday) seemed to confirm that we have pretty good pace. But there are still other quick cars out there, and we can't go into (Saturday's final practice and qualifying) sessions not thinking that they will be close."

While Hamilton and Rosberg were in a league of their own last year, it could be a different story for the Mercedes duo this season. Sebastian Vettel, the four-time F1 world champion, is now with Ferrari, teaming up with Kimi Raikkonen. Vettel had a disappointing season in '14, his last with Red Bull. He failed to win a race and placed fifth in the world championship point standings.

Vettel, making his competition debut with Ferrari this weekend in Melbourne, had the fifth fastest time in the first practice (1:31.029) and the third quickest lap in P2 (1:28.412).

"It was a good day with no problems on the car," Vettel said. It looks like the hard work done during the winter, both on track and at the factory at Maranello (Italy), is paying off."

Ferrari has not won a race since the May 2013 Spanish Grand Prix, with driver Fernando Alonso, and Vettel's last victory in a grand prix occurred in the '13 season-finale in Brazil.

Alonso returned to McLaren for this season after driving for that team in 2007. He will miss the Australian GP due to a concussion he suffered during an accident in preseason testing last month in Barcelona. He is expected to return for the Malaysian Grand Prix the last weekend in March. Kevin Magnussen, the test and reserve driver for McLaren, will fill-in for Alonso in Australia.

Series: Formula One. Date: Sunday, March 15. Race: Australian Grand Prix. Site: Albert Park Circuit. Track: 3.3-mile (5.303-kilometer), 16-turn temporary street circuit. Start Time: 1 a.m. ET. Laps: 58. Miles: 191.110 (307.574 km). 2014 Winner: Nico Rosberg. Television: NBC Sports Network.